Fatigue and fracture behavior in notched specimens of C/C composite with fine-woven carbon fiber laminates

Fatigue and fracture behavior of C/C composite with fine-woven carbon fiber laminates was investigated in several schemes of notched specimens. Slits and holes were cut in the specimens as notches, and the effect of fiber orientation and notch configuration on the fatigue behavior was examined. The fatigue limit was defined by a simple method that used incremental applied stress and number of cycles. The fatigue limit was dependent on fiber orientation, notch configuration and stress ratio (ratio of minimum cyclic stress to maximum cyclic stress). It was found that the fatigue limit was determined by the true stress rather than by the stress concentration in the present material and was not affected by variations in slit depth. Also, the fracture behavior was controlled by shear deformation.     

Non-oxidative thermal degradation of amines: GCMS/FTIR spectra analysis and molecular modeling

Aqueous amino solvents, such as monoethanolamine (ETA/MEA), methyl diethanolamine (MDEA) or amine blends, are the most widely used solvents in commercial CO₂ or acid gas separation applications. These commercial solvents have various disadvantages, such as the possibilities of the solvent to be degraded. This research examines the impact of non-oxidative thermal degradations on the performance of the CO₂ absorption and the degradation mechanism of amine solvents. The impact of degradation was conducted by measuring the CO₂ solubility of solvent that had been heated to 120°C for 2 h. Although the performance of CO₂ absorption was not significantly reduced, the degradation of amines was found. Supported by Fourier Transform Infrared (FTIR) and Gas Chromatography/Mass Spectrometer result, the suspected products of non-oxidative thermal degradation of MDEA were MEA and acetone.